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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@kernel.org>,
	Balbir Singh <bsingharora@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Weijiang Yang <weijiang.yang@intel.com>,
	Pengfei Xu <pengfei.xu@intel.com>,
	Haitao Huang <haitao.huang@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v26 22/30] x86/cet/shstk: Add user-mode shadow stack support
Date: Tue, 27 Apr 2021 13:43:07 -0700	[thread overview]
Message-ID: <20210427204315.24153-23-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20210427204315.24153-1-yu-cheng.yu@intel.com>

Introduce basic shadow stack enabling/disabling/allocation routines.
A task's shadow stack is allocated from memory with VM_SHADOW_STACK flag
and has a fixed size of min(RLIMIT_STACK, 4GB).

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
---
v25:
- Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK.
- Update alloc_shstk(), remove unused input flags.

v24:
- Rename cet.c to shstk.c, update related areas accordingly.

 arch/x86/include/asm/cet.h       |  29 ++++++++
 arch/x86/include/asm/processor.h |   5 ++
 arch/x86/kernel/Makefile         |   2 +
 arch/x86/kernel/shstk.c          | 123 +++++++++++++++++++++++++++++++
 4 files changed, 159 insertions(+)
 create mode 100644 arch/x86/include/asm/cet.h
 create mode 100644 arch/x86/kernel/shstk.c

diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
new file mode 100644
index 000000000000..aa85d599b184
--- /dev/null
+++ b/arch/x86/include/asm/cet.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_CET_H
+#define _ASM_X86_CET_H
+
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+
+struct task_struct;
+/*
+ * Per-thread CET status
+ */
+struct cet_status {
+	unsigned long	shstk_base;
+	unsigned long	shstk_size;
+};
+
+#ifdef CONFIG_X86_SHADOW_STACK
+int shstk_setup(void);
+void shstk_free(struct task_struct *p);
+void shstk_disable(void);
+#else
+static inline int shstk_setup(void) { return 0; }
+static inline void shstk_free(struct task_struct *p) {}
+static inline void shstk_disable(void) {}
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_CET_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index f1b9ed5efaa9..3690b78e55bb 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -27,6 +27,7 @@ struct vm86;
 #include <asm/unwind_hints.h>
 #include <asm/vmxfeatures.h>
 #include <asm/vdso/processor.h>
+#include <asm/cet.h>
 
 #include <linux/personality.h>
 #include <linux/cache.h>
@@ -535,6 +536,10 @@ struct thread_struct {
 
 	unsigned int		sig_on_uaccess_err:1;
 
+#ifdef CONFIG_X86_SHADOW_STACK
+	struct cet_status	cet;
+#endif
+
 	/* Floating point and extended processor state */
 	struct fpu		fpu;
 	/*
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 2ddf08351f0b..0f99b093f350 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -150,6 +150,8 @@ obj-$(CONFIG_UNWINDER_FRAME_POINTER)	+= unwind_frame.o
 obj-$(CONFIG_UNWINDER_GUESS)		+= unwind_guess.o
 
 obj-$(CONFIG_AMD_MEM_ENCRYPT)		+= sev-es.o
+obj-$(CONFIG_X86_SHADOW_STACK)		+= shstk.o
+
 ###
 # 64 bit specific files
 ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
new file mode 100644
index 000000000000..c815c7507830
--- /dev/null
+++ b/arch/x86/kernel/shstk.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * shstk.c - Intel shadow stack support
+ *
+ * Copyright (c) 2021, Intel Corporation.
+ * Yu-cheng Yu <yu-cheng.yu@intel.com>
+ */
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/sched/signal.h>
+#include <linux/compat.h>
+#include <linux/sizes.h>
+#include <linux/user.h>
+#include <asm/msr.h>
+#include <asm/fpu/internal.h>
+#include <asm/fpu/xstate.h>
+#include <asm/fpu/types.h>
+#include <asm/cet.h>
+
+static void start_update_msrs(void)
+{
+	fpregs_lock();
+	if (test_thread_flag(TIF_NEED_FPU_LOAD))
+		__fpregs_load_activate();
+}
+
+static void end_update_msrs(void)
+{
+	fpregs_unlock();
+}
+
+static unsigned long alloc_shstk(unsigned long size)
+{
+	struct mm_struct *mm = current->mm;
+	unsigned long addr, populate;
+	int flags = MAP_ANONYMOUS | MAP_PRIVATE;
+
+	mmap_write_lock(mm);
+	addr = do_mmap(NULL, 0, size, PROT_READ, flags, VM_SHADOW_STACK, 0,
+		       &populate, NULL);
+	mmap_write_unlock(mm);
+
+	return addr;
+}
+
+int shstk_setup(void)
+{
+	unsigned long addr, size;
+	struct cet_status *cet = &current->thread.cet;
+
+	if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+		return -EOPNOTSUPP;
+
+	size = round_up(min_t(unsigned long long, rlimit(RLIMIT_STACK), SZ_4G), PAGE_SIZE);
+	addr = alloc_shstk(size);
+	if (IS_ERR_VALUE(addr))
+		return PTR_ERR((void *)addr);
+
+	cet->shstk_base = addr;
+	cet->shstk_size = size;
+
+	start_update_msrs();
+	wrmsrl(MSR_IA32_PL3_SSP, addr + size);
+	wrmsrl(MSR_IA32_U_CET, CET_SHSTK_EN);
+	end_update_msrs();
+	return 0;
+}
+
+void shstk_free(struct task_struct *tsk)
+{
+	struct cet_status *cet = &tsk->thread.cet;
+
+	if (!cpu_feature_enabled(X86_FEATURE_SHSTK) ||
+	    !cet->shstk_size ||
+	    !cet->shstk_base)
+		return;
+
+	if (!tsk->mm)
+		return;
+
+	while (1) {
+		int r;
+
+		r = vm_munmap(cet->shstk_base, cet->shstk_size);
+
+		/*
+		 * vm_munmap() returns -EINTR when mmap_lock is held by
+		 * something else, and that lock should not be held for a
+		 * long time.  Retry it for the case.
+		 */
+		if (r == -EINTR) {
+			cond_resched();
+			continue;
+		}
+		break;
+	}
+
+	cet->shstk_base = 0;
+	cet->shstk_size = 0;
+}
+
+void shstk_disable(void)
+{
+	struct cet_status *cet = &current->thread.cet;
+	u64 msr_val;
+
+	if (!cpu_feature_enabled(X86_FEATURE_SHSTK) ||
+	    !cet->shstk_size ||
+	    !cet->shstk_base)
+		return;
+
+	start_update_msrs();
+	rdmsrl(MSR_IA32_U_CET, msr_val);
+	wrmsrl(MSR_IA32_U_CET, msr_val & ~CET_SHSTK_EN);
+	wrmsrl(MSR_IA32_PL3_SSP, 0);
+	end_update_msrs();
+
+	shstk_free(current);
+}
-- 
2.21.0


  parent reply	other threads:[~2021-04-27 20:45 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-27 20:42 [PATCH v26 00/30] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 01/30] Documentation/x86: Add CET description Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 02/30] x86/cet/shstk: Add Kconfig option for Shadow Stack Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 03/30] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 04/30] x86/cpufeatures: Introduce CPU setup and option parsing for CET Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 05/30] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 06/30] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 07/30] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 08/30] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 09/30] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 10/30] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 11/30] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 12/30] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 13/30] mm: Introduce VM_SHADOW_STACK for shadow stack memory Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 14/30] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 15/30] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 16/30] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 17/30] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 18/30] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 19/30] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 20/30] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 21/30] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-04-27 20:43 ` Yu-cheng Yu [this message]
2021-04-28 17:52   ` [PATCH v26 22/30] x86/cet/shstk: Add user-mode shadow stack support Borislav Petkov
2021-04-28 18:39     ` Yu, Yu-cheng
2021-04-29  9:12       ` Borislav Petkov
2021-04-29 16:17         ` Yu, Yu-cheng
2021-04-29 16:45           ` Borislav Petkov
2021-04-27 20:43 ` [PATCH v26 23/30] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-05-10 14:15   ` Borislav Petkov
2021-05-10 22:57     ` Yu, Yu-cheng
2021-05-11 17:09       ` Borislav Petkov
2021-05-12  8:12         ` David Laight
2021-05-11 18:35     ` Yu, Yu-cheng
2021-05-12 15:56       ` Borislav Petkov
2021-04-27 20:43 ` [PATCH v26 24/30] x86/cet/shstk: Introduce shadow stack token setup/verify routines Yu-cheng Yu
2021-05-17  7:45   ` Borislav Petkov
2021-05-17 20:55     ` Yu, Yu-cheng
2021-05-18  0:14       ` Eugene Syromiatnikov
2021-05-18 17:58         ` Borislav Petkov
2021-05-18 19:45           ` Yu, Yu-cheng
2021-05-18 18:05         ` Yu, Yu-cheng
2021-05-18  5:56       ` Borislav Petkov
2021-05-21 16:17     ` Yu, Yu-cheng
2021-05-21 18:40       ` Borislav Petkov
2021-04-27 20:43 ` [PATCH v26 25/30] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-04-28 23:03   ` extending ucontext (Re: [PATCH v26 25/30] x86/cet/shstk: Handle signals for shadow stack) Andy Lutomirski
2021-04-28 23:03     ` Andy Lutomirski
2021-04-28 23:20     ` Yu, Yu-cheng
2021-04-29  7:28     ` Cyrill Gorcunov
2021-04-29 14:44       ` Andy Lutomirski
2021-04-29 14:44         ` Andy Lutomirski
2021-04-29 15:35         ` Cyrill Gorcunov
2021-04-30  6:45     ` Florian Weimer
2021-04-30  6:45       ` Florian Weimer
2021-04-30 17:00     ` Yu, Yu-cheng
2021-04-30 17:47       ` Andy Lutomirski
2021-04-30 17:47         ` Andy Lutomirski
2021-04-30 18:32         ` Yu, Yu-cheng
2021-05-04 20:49           ` Yu, Yu-cheng
2021-05-06 22:05             ` Yu, Yu-cheng
2021-05-06 23:31               ` Andy Lutomirski
2021-05-06 23:31                 ` Andy Lutomirski
2021-05-02 23:23         ` Andy Lutomirski
2021-05-02 23:23           ` Andy Lutomirski
2021-05-03  6:03           ` H. Peter Anvin
2021-05-03 15:13           ` Yu, Yu-cheng
2021-05-03 15:29             ` Andy Lutomirski
2021-05-03 20:25               ` Yu, Yu-cheng
2021-04-27 20:43 ` [PATCH v26 26/30] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-05-19 18:10   ` Borislav Petkov
2021-05-19 22:14     ` Yu, Yu-cheng
2021-05-20  9:26       ` Borislav Petkov
2021-05-20 17:18         ` Yu, Yu-cheng
2021-05-20 17:35           ` Borislav Petkov
2021-05-20 17:51             ` Yu, Yu-cheng
2021-05-20 17:38       ` Matthew Wilcox
2021-05-20 17:52         ` Yu, Yu-cheng
2021-05-20 21:06           ` Yu, Yu-cheng
2021-04-27 20:43 ` [PATCH v26 27/30] x86/cet/shstk: Add arch_prctl functions for shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 28/30] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 29/30] mm: Update arch_validate_flags() to test vma anonymous Yu-cheng Yu
2021-05-11 11:35   ` Kirill A. Shutemov
2021-04-27 20:43 ` [PATCH v26 30/30] mm: Introduce PROT_SHADOW_STACK for shadow stack Yu-cheng Yu
2021-05-11 11:48   ` Kirill A. Shutemov
2021-05-11 14:44     ` Yu, Yu-cheng
2021-04-29 17:13 ` [PATCH v26 00/30] Control-flow Enforcement: Shadow Stack Borislav Petkov
2021-04-29 17:32   ` Yu, Yu-cheng
2021-04-29 17:49     ` Borislav Petkov

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